The present invention is directed to a dispensing package, particularly for dispensing a flowable viscous material. More particularly, the present invention is directed to a dispensing package for dispensing a cream product, such as a cream deodorant or cream antiperspirant product, for application to axillary regions of the human body.
Dispensing packages, for dispensing cream products, such as cream deodorant or cream antiperspirant products, are known. Typically, the product is extruded out of an outlet (for example, outlet slots) in a top end of the dispensing package, by manually turning a hand wheel (thumb wheel), which drives a feed screw and, in turn, an elevator. Moving the elevator decreases the volume of an interior chamber of the dispensing package which contains the product; this pressurizes the product, causing the product to be extruded through the outlet slots onto an applicator surface desirably forming the top end of the dispensing package.
A problem with this type of dispensing package is a weeping of the product onto the applicator surface, after a desired amount of the product has already been dispensed from the package. Such weeping is caused due to residual pressure on the product in the interior chamber of the dispensing package, after the desired amount of the product has been extruded through the outlet.
An approach to solving this problem of weeping of product onto the applicator surface is described in U.S. Pat. No. 5,000,356 to Johnson, et al, the contents of which are incorporated herein by reference in their entirety. Briefly, the dispensing package disclosed in U.S. Pat. No. 5,000,356 includes a container body which has a uniform cross-sectional interior chamber to hold the product. The container body has a lengthwise central axis, an elevator congruent to and which axially moves within the container body, forming a movable surface of the interior chamber, and a feed screw to cause the elevator to advance axially forward while axially reciprocating the elevator one cycle for each increment of forward motion. The aforementioned weeping is avoided by providing the reciprocating movement of the elevator, superimposing axial reciprocative displacement onto the unidirectional axial advance of the elevator. By providing the reciprocating displacement of the elevator, the elevator automatically can be retracted from the product in the interior chamber upon dispensing of product (that is, the volume of the interior chamber can be increased), thereby relieving the residual pressure caused by the forward stroke of the elevator.
U.S. Pat. No. 5,000,356 discloses structure for providing the reciprocating displacement, including a camming surface of the bottom of the container body and a corresponding follower surface fixed to the feed screw. This U.S. Pat. No. 5,000,356 discloses providing a biasing spring between the thumb wheel and the feed screw on which the elevator is provided, to bias the feed screw (and elevator) away from the product, thereby forcing retraction of the elevator from the product (on the camming surface of the bottom of the container body). Moreover, this U.S. Pat. No. 5,000,356 discloses that the camming surface on the container, as well as the follower fixed to the feed screw, should each be a sawtooth structure.
However, various problems arise in connection with the structure disclosed in U.S. Pat. No. 5,000,356. A relatively weak spring action is provided biasing the feed screw toward the camming surface of the container body, for reciprocatingly drawing the elevator away from the product. According to the structure in U.S. Pat. No. 5,000,356, wherein the spring action is provided between the feed screw and thumb wheel, such spring action must overcome friction between the elevator and container sides; this acts as a limit on the seal which can be utilized between the elevator and container sides. Because the spring action is relatively weak, the elevator must be relatively loosely fitting against the sides of the container body, so that the spring can be effective in forcing the follower downward against the camming surface. However, with such relatively loose fit of the elevator in the container body, the problem arises that the product can leak out of the interior chamber, between the sides of the container body and the elevator. A further problem arises in that the sawtooth camming surface and sawtooth follower make it difficult to turn the thumb wheel so as to propel the elevator toward the product while providing reciprocating movement of the elevator, and especially makes it difficult to retract the elevator axially (that is, to turn the thumb wheel in a direction opposite to that causing the forward stroke).
Accordingly, it is still desired to provide a dispensing package for flowable viscous products (for example, for a cream deodorant or antiperspirant product), wherein leakage (either weeping onto an applicator surface or leakage between sides of the container body and the elevator) from the package is avoided, while the product can easily be applied from the dispensing package by a consumer.